Internal combustion engines are known to use reciprocating piston and rotary designs. In U.S. Pat. No. 5,033,429 (the '429 patent), Groves discloses a particular rotary type internal combustion engine comprising a plurality of vanes disposed on ends of lever arms, the vanes compressing combustible fluid in combustion chambers and harnessing energy released during combustion. A plurality of lever arms extend radially from a common center, and force transmits along the lever arms from the vanes to the common center. At the common center, the force transfers through a flexible joint to rotate a shaft.
The engine disclosed in '429 is simple and efficient, having relatively few moving parts and losing no mechanical energy to reciprocation of the pistons. However, the '429 engine relies solely on positive pressure from combustion to exhaust combustion products from the engine, a space in which the combustion products reside being unswept. Moreover, combustion places large lateral forces on the lever arms, which comprise elongate shafts that are relatively ill adapted to withstand lateral stress.